Drafting arrangement for a knitting machine

ABSTRACT

A drafting arrangement for a knitting machine for the production of a fiber structure includes a roving with double aprons guided over apron rollers and an output roller pair. The apron rollers and the output roller pair respectively have a press roller and an electric motor-driven drive roller and the rollers and the electric motors are arranged on the front side of a base plate. Motor shafts are passed through the base plate and are connected by means of drive devices to the shaft members of the drive rollers. A clamping device is provided on the rear side (18) of the base plate (11) to press apron rollers and the output roller pair against the drive rollers.

The invention relates to a drafting arrangement for a knitting machine for the production of a fibre structure consisting of a roving with double aprons guided over apron rollers and an output roller pair, wherein the apron rollers and the output roller pair respectively have a press roller and an electric motor-driven drive roller and the rollers and the electric motors are arranged on the front side of a base plate, whereas the motor shafts are passed through the base plate and are connected by means of drive devices to the shaft members of the drive rollers mounted in the base plate.

Such drafting arrangements have already been described in WO 2009/026734 A1. They serve to produce a drawn fibre structure from a roving and to feed this directly to the needles of a knitting machine. The knitted pieces produced from the fibre structure, which has substantially parallel oriented fibres, feel considerably softer than knitted pieces produced from a finished-spun yarn. The process of yarn spinning becomes unnecessary if knitting machines are fitted with such drafting arrangements. The knitted goods are fabricated directly from the roving.

In the known drafting arrangements all parts, except for the toothed belt drive for the bottom rollers, are located on the front side of the base plate of the drafting arrangement. However, as a result, these drafting arrangement parts are also exposed to fibre fly, which unavoidably occurs during passage of the fibre structure through the drafting arrangement, and therefore are quickly soiled. However, cleaning of the drafting arrangement is very tedious because of the plurality of component parts attached to the front side of the base plate.

Therefore, the object forming the basis for the present invention is to propose a drafting arrangement for a knitting machine, in which less stress on the component parts results as a result of fibre fly and which is easier to clean.

The object is achieved by a drafting arrangement for a knitting machine for the production of a fibre structure consisting of a roving with double aprons guided over apron rollers and an output roller pair, wherein the apron rollers and the output roller pair respectively have a press roller and an electric motor-driven drive roller and the rollers and the electric motors are arranged on the front side of a base plate, whereas the motor shafts are passed through the base plate and are connected by means of drive devices to the shaft members of the drive rollers mounted in the base plate, which is characterised in that a clamping device is provided on the rear side of the base plate, with which clamping device the press rollers of the apron roller pair and the output roller pair can be pressed against the drive rollers.

The clamping device, with which the press rollers can be pressed against the driven rollers to enable the fibre structure to be drawn, is also arranged on the front side above the press rollers in the known drafting arrangements. Since each of the press rollers must be acted on by the clamping device, this has a relatively large number of components, which when arranged on the front side of the drafting arrangement, i.e. on the side where the fibre structure passes through, are exposed to fibre fly and thus become soiled. They must be cleaned regularly and, moreover, make cleaning of the roller pairs and aprons difficult, since they hinder direct access to these from above.

In the drafting arrangement according to the invention all the components of the clamping device are arranged on the rear side of the drafting arrangement, where they cannot become soiled by fibre fly and do not block free access to the roller pairs and aprons on the front side. As a result, the drafting arrangement according to the invention is clearly more maintenance-friendly than the known drafting arrangements.

In a preferred configuration of the drafting arrangement, the shaft members of the press rollers are guided through openings in the base plate with play and are movable up and down in the openings by the clamping device. When the clamping device is relaxed, the rollers can be moved by hand within the play allowed by the openings to be able to replace and/or clean an apron or one of the rollers, for example.

It is of advantage in this case if the shaft members of the press rollers are rotatably mounted in slides on the rear side of the base plate, wherein a spring force can be applied to the slides by the clamping device. The slides, which can be mounted in guides, allow a precise movement of the press roller shaft members by the spring force generated by the clamping device, wherein this spring force can be generated by springs associated with each of the slides.

It is of further advantage in this configuration of the clamping device if the clamping device has a rail, which extends over the slides and is displaceably arranged on the base plate and with which the contact pressure can be generated. The press rollers can thus be pressed against the drive rollers or relieved of pressure by simple displacement of this rail. For this, the rail can be arranged to be longitudinally displaceable on the base plate and can be provided with cams, wherein the cams of the rail act on the springs interacting with the slides. Leg springs can preferably be used as springs. These can be arranged in an adjustable spring block, so that the spring force generated by the springs can be adjusted by displacement of the spring block.

However, the drafting arrangement according to the invention can also have a pneumatic, hydraulic or electric clamping device instead of a mechanical clamping device.

In this case, the clamping device can be activated and deactivated in a manner known per se by a swivelling lever connected to the clamping device. The swivelling lever can be arranged outside the housing of the plate to be easily accessible in this case.

The drafting arrangement can be configured in different ways, depending on the roving to be processed. So-called 3-roller drafting arrangements are used relatively frequently, i.e. in addition to the apron rollers and the output roller pair the drafting arrangement can have an input roller pair, the press roller of which can also be acted on by the clamping device.

As a further measure to reduce soiling of the drafting arrangement by fibre fly, the motors can be protected from fibre fly by a removable covering. Moreover, a suction means, through which fibres and dust can be aspirated before they are deposited onto drafting arrangement parts, can be arranged on the output roller pair.

Even if the rear side of the drafting arrangement does not come into direct contact with the fibre structure, it is further expedient to also protect the rear side of the base plate by means of a removable housing cover.

The invention further relates to a knitting machine, preferably a circular knitting machine, which is equipped with at least one drafting arrangement according to the invention.

A preferred exemplary embodiment of a drafting arrangement according to the invention will be described below with reference to the drawing.

FIG. 1 is a perspective view onto the front side of a drafting arrangement;

FIG. 2 is a view of the rear side of the drafting arrangement from FIG. 1;

FIG. 3 is a detail view of the rear side of the drafting arrangement from FIG. 1 with active clamping device;

FIG. 4 is a view corresponding to FIG. 3 with inactive clamping device;

FIG. 5 is an enlarged detail view of the rear side of the drafting arrangement from FIG. 1;

FIG. 6 is an enlarged detail view of the axial passages through the base plate of the drafting arrangement from FIG. 1.

The drafting arrangement 10 from FIG. 1 has a base plate 11, on the front side 12 of which are arranged two motors 13, 14, an input roller pair 15, an apron roller pair 16 and an output roller pair 17. Each of the roller pairs 15, 16, 17 consists of a lower driven roller 15.1, 16.1, 17.1 and an upper press roller 15.2, 16.2, 17.2. The fibre structure that is to be drawn by the drafting arrangement and is not represented in further detail is passed respectively between the upper and lower drive rollers 15.2, 16.2, 17.2 and 15.1, 16.1, 17.1. The desired drafting of the fibre structure is achieved by the different speeds of the roller pairs.

The motors 13, 14 are protected from fibre fly by a covering that is omitted from FIG. 1. Moreover, a suction device, which has also been omitted from the figure for reasons of clarity, is provided on the output roller pair 17.

FIG. 2 shows the rear side 18 of the base plate 11, on which an electronic control part 19 and also a mechanical part 20 of the drafting arrangement 10 are arranged. The more precise structure of the mechanical part 20 is shown in FIGS. 3 to 6. Both the electronic part 19 and the mechanical part 20 are covered to the outside by a housing cover, which is, however, not shown here in order to provide a free view onto the components of the drafting arrangement 10.

It can be seen from FIG. 3 that shafts 13.1, 14.1 of the motors 13, 14 are passed through the base plate 11 onto the rear side 18. There, the shaft member 17.3 of the output drive roller 17.1 that is likewise passed through the base plate 11 is driven by means of the shaft 13.1 with the aid of a toothed belt 21, whereas shaft 14.1 drives shaft members 16.3, 15.3 of the apron drive roller 16.1 and the input drive roller 15.1 by means of a toothed belt 22 and several pinions. A clamping device 25 for the upper press rollers 15.2, 16.2, 17.2 is additionally arranged on the rear side 18 of the base plate 11. It has a spring block 26, in which three leg springs 27, 28, 29 are mounted. In addition, a rail 30, which is connected to a clamping lever 31, is displaceably mounted in the spring block 26.

In FIG. 3 the rail 30 has been displaced inwards in the direction of the arrow by closing the clamping lever 31. As a result of this, cams 32 (FIG. 4) provided on the rail press onto the leg springs 27, 28, 29, the second leg of which is itself acted on respectively by a slide 33, 34, 35 (FIG. 4). The slides 33, 34, 35 are pressed downwards as a result.

In FIG. 4 on the other hand, the clamping leer 31 has been opened, as a result of which the rail 30 has been moved outwards in the direction of the arrow. As a result, the cams 32 are no longer in contact with the leg springs 27, 28, 29. The slides 33, 34, 35 are not pressed further downwards.

As is clear in FIG. 5 and FIG. 6, shaft members 15.4, 16.4, 17.4 of the press rollers 15.2, 16.2, 17.2 are respectively mounted in the slides 33, 34, 35. In this case, these shaft members 15.4, 16.4 and 17.4 are passed through openings 36 in the base plate 19 with play. If the slides 33, 34, 35 are not pressed downwards by means of the clamping device 25, then the upper press rollers 15.2, 16.2, 17.2 also move downwards and thus generate the necessary contact pressure of the fibre structure against the drive rollers 15.1, 16.1, 17.1. However, if the clamping device 25 is inactive (FIG. 4), then the upper press rollers 15.2, 16.2, 17.2 can be moved upwards by hand so far as the play between the shaft members 15.4, 16.4, 17.4 and the openings 36 permits. 

1. A drafting arrangement for a knitting machine for the production of a fiber structure, comprising: a roving with double aprons guided over apron rollers; and an output roller pair; wherein the apron rollers and the output roller pair respectively have a press roller and an electric motor-driven drive roller; wherein the press rollers, the electric motor-driven drive rollers and electric motors are arranged on a front side of a base plate, whereas motor shafts are passed through the base plate and are connected by means-of-drive devices to shaft members of the electric motor-driven drive rollers mounted in the base plate; and wherein a clamping device is provided on a the-rear side of the base plate to press the press rollers of the apron roller pair and the output roller pair against the electric motor-driven drive rollers.
 2. The drafting arrangement according to claim 1, wherein the shaft members of the press rollers are guided through openings in the base plate (11) with play and are movable up and down in the openings by the clamping device.
 3. The drafting arrangement according to claim 1, wherein the shaft members of the press rollers are rotatably mounted in slides on a rear side of the base plate, and wherein a spring force is applied to the slides by the clamping device.
 4. The drafting arrangement according to claim 3, wherein each slide has an associated spring.
 5. The drafting arrangement according to claim 3, wherein the clamping device has a rail, which extends over the slides and is displaceably arranged on the base plate and with which the contact pressure is generated.
 6. The drafting arrangement according to claim 5, wherein the rail is arranged to be longitudinally displaceable on the base plate and is provided with cams, and wherein the cams act on springs interacting with the slides.
 7. The drafting arrangement according to claim 6, wherein the springs are leg springs.
 8. The drafting arrangement according to claim 6, wherein the springs are arranged in an adjustable spring block.
 9. The drafting arrangement according to claim 1, wherein the clamping device is activated by a manually operable clamping lever.
 10. The drafting arrangement according to claim 1 wherein, an input roller pair-includes a further press roller that also is acted on by the clamping device, and wherein the further press roller, is additionally arranged on the base plate.
 11. The drafting arrangement according to claim 1, wherein the motors are protected from fiber fly by a removable covering.
 12. The drafting Drafting-arrangement according to claim 1, wherein a suction means is arranged on the output roller pair.
 13. The drafting arrangement according to claim 1, wherein the rear side of the base plate is protected from fiber fly by removable housing cover.
 14. A knitting machine with at least one drafting arrangement according to claim
 1. 